FIELD OF THE INVENTION
Gelatin-based thermal insulation is described. The thermal insulation is obtained utilizing foamed compositions containing ingredients which provide advantageous properties to the gelatin-foam.
Thermal insulation continues to be an important field for development. Although developments in insulation have been made, there are still a number of drawbacks to traditional insulation materials. Many inorganic materials are friable, have health hazards, and tend to be high in density. With the organic insulation, combustibility, toxicity, smoke, and environmental hazards continue to be a concern where the insulation is used.
Gelatin foam has been suggested as an appropriate insulation in U.S. Pat. No 4,331,547. As an insulation, however, the foam has disadvantages which are inherent in the gelatin foam itself. Specifically, gelatin foam is plagued with shrinkage, both as it dries and under humid or moist conditions.
Insulation shrinkage is, therefore, a problem for gelatin-based insulation, particularly when the foam is cast into a shape such as a cylinder. Such shrinkage results in severely distorted shapes which must be machined or ground, resulting in high scrap levels.
When gelatin foam contacts water it characteristically pulls water into the dry areas of the foam, a process known as "wicking". This severely limits the utility of the gelatin foam insulation since some applications require insulation which is resistant to wicking water.
It would be desirable and advantageous to provide a gelatin foam insulation that is resistant to both wicking and shrinkage on drying. At the same time this insulation should maintain good to excellent standards in the other characteristics needed for good insulation. Thus, the insulation should be non-toxic, and it should be fire resistant and emit little smoke during combustion and, of course, it should possess reasonable thermal conductivity.
The present invention has provided such insulation. Specifically, thermally insulative compositions described herein contain an ingredient that makes the foam resistant to wicking. In addition to this, other embodiments provide foam that is resistant to shrinkage during drying. Still another embodiment provides a foam insulation which is resistant to shrinking when it is wet. This insulation, in fact, is spongy when it is wet and has shape memory. At the same time, the gelatin foam has fire resistance, low smoke, environmental safety, and an appropriate thermal conductivity.